U.S. patent number 7,198,387 [Application Number 11/016,449] was granted by the patent office on 2007-04-03 for light fixture for an led-based aircraft lighting system.
This patent grant is currently assigned to B/E Aerospace, Inc.. Invention is credited to Jennifer L. Gloisten, Tolek Pawelko.
United States Patent |
7,198,387 |
Gloisten , et al. |
April 3, 2007 |
Light fixture for an LED-based aircraft lighting system
Abstract
A light fixture for housing LED units is provided. The light
fixture has a housing that has a substantially H-shaped cross
section. The housing has a crossbar with a series of mesas defined
on its upper surface. A group of LED units is attached to each of
the series of mesas, each LED unit being attached with a thin layer
of adhesive. The LED units are electrically insulated from the
housing by either the adhesive, which may be electrically
insulating, or by an electrically insulating coating on the
housing.
Inventors: |
Gloisten; Jennifer L.
(Farmingville, NY), Pawelko; Tolek (Deer Park, NY) |
Assignee: |
B/E Aerospace, Inc.
(Wellington, FL)
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Family
ID: |
37897542 |
Appl.
No.: |
11/016,449 |
Filed: |
December 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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60530492 |
Dec 18, 2003 |
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Current U.S.
Class: |
362/294; 362/545;
362/238; 362/218 |
Current CPC
Class: |
F21V
15/01 (20130101); F21V 29/75 (20150115); F21V
29/767 (20150115); F21V 23/006 (20130101); B60Q
3/43 (20170201); B60Q 3/47 (20170201); F21S
4/20 (20160101); H05K 1/0204 (20130101); F21Y
2115/10 (20160801); F21Y 2103/10 (20160801) |
Current International
Class: |
F21V
29/00 (20060101); F21S 8/10 (20060101); F21V
1/00 (20060101); F21V 7/20 (20060101) |
Field of
Search: |
;362/249,219,294,800,218,227,231,240,235-238,457,545,555 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ward; John Anthony
Assistant Examiner: Makiya; David
Attorney, Agent or Firm: Drinker Biddle & Reath LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of the filing date of
U.S. Provisional Application No. 60/530,492, filed Dec. 18, 2003,
which is hereby incorporated by reference in its entirety.
Claims
What is claimed is:
1. A light fixture comprising: a housing made of thermally
conductive material, wherein the housing includes a first side, a
second side, and a crossbar connecting the first side to the second
side, wherein the second side is displaced from the first side,
wherein the crossbar has an upper surface and a lower surface, and
the printed circuit board is attached to the upper surface of the
crossbar, a printed circuit board supported by the housing; and a
light emitting diode unit that is mounted on the housing with a
layer of adhesive, the light emitting diode having leads that are
electrically connected to the printed circuit board, wherein an
electrically insulating material is disposed between the light
emitting diode unit and the housing, wherein at least one mesa
extends along the upper surface of the crossbar, the printed
circuit board includes an opening that accommodates a metal back
surface of the light emitting diode unit, and a thermal path
extends from back surface of the light emitting diode unit to the
at least one mesa.
2. The light fixture of claim 1, wherein the light emitting diode
unit is part of a group of light emitting diode units, wherein the
group of light emitting diode units includes light emitted diode
units that each emit light whose color is different than the light
of the other light emitting diode units of the group.
3. The light fixture of claim 1, wherein the layer of adhesive has
a low thermal conductivity.
4. The light fixture of claim 1, wherein the layer of adhesive
material is electrically insulating.
5. The light fixture of claim 1, wherein the housing is made of
aluminum.
6. The light fixture of claim 1, wherein the electrically
insulating material is the layer of adhesive.
7. The light fixture of claim 1, wherein the layer of adhesive is
electrically conductive.
8. The light fixture of claim 1, wherein the metal back surface of
the light emitting diode unit is attached to the mesa through the
opening.
9. The light fixture of claim 1, wherein the housing comprises a
thermally conductive material that is coated with a finish that
inhibits the flow of electric current.
10. The light fixture of claim 1, wherein the layer of adhesive has
a low thermal conductivity, the layer being sufficiently thin to
permit head to dissipate into the housing from the light-emitting
diode unit.
11. A light fixture comprising: a housing comprising: a first side
and a second side, the first side comprising an inner surface
having a substantially straight portion, the second side comprising
an inner surface having a substantially straight portion, wherein
the inner surface of the first side of the housing has an angled
portion, and the inner surface of the second side of the housing
has an angled portion, wherein the angled portions of the inner
surfaces of each of the first and second sides are covered in a
reflective material, the effect of which is to approximate a
parabolic reflector; a crossbar attached to the substantially
straight portion of the first side and to the substantially
straight portion of the second side, the cross bar comprising an
upper surface and a lower surface, wherein a mesa is defined on the
upper surface, the mesa being substantially parallel to the
straight portions of the first and second sides of the housing; a
light emitting diode unit having a lens, a base portion, a first
lead, and a second lead, wherein the base portion is attached to
the mesa with a non-conductive adhesive, a circuit board disposed
on the upper surface of the crossbar; and a first conductor run and
a second conductor run disposed on the circuit board, wherein the
first lead of the light emitting diode unit is electrically
connected to the first conductor run and the second lead of the
light emitting diode unit is electrically connected to the second
conductor run.
12. The light fixture of claim 11, the housing comprises a
thermally conductive material that is coated with a finish that
inhibits the flow of electric current.
13. The light fixture of claim 11, wherein the reflective material
is reflective tape.
14. The light fixture of claim 11, further comprising a copper
ground plane disposed on top of the circuit board.
15. A light fixture comprising: a housing having a top, and a
bottom, the housing comprising: a first side and a second side, the
first side comprising an inner surface having a substantially
straight portion, the second side comprising an inner surface
having a substantially straight portion; a crossbar attached to the
substantially straight portion of the first side and to the
substantially straight portion of the second side, the cross bar
comprising an upper surface and a lower surface, wherein a mesa is
defined on the upper surface, the mesa being substantially parallel
to the straight portions of the first and second sides of the
housing, wherein the upper surface of the crossbar faces the top of
the housing and the lower surface of the crossbar faces the bottom
of the housing; a lens including a first end and a second end, the
lens being formed with a downward fold at the first end and a
downward fold at the second end, the lens being disposed on the top
of the housing such that it acts as an end closure; a cover
disposed on the bottom of the housing, wherein the edges of the
cover fold upward such that they are oriented in substantially the
same direction as the first and second sides of the housing,
wherein the downward end folds of the lens of the housing are
constrained by the upwardly folded edges of the cover; a light
emitting diode unit having a lens, a base portion, a first lead,
and a second lead, wherein the base portion is attached to the mesa
with a non-conductive adhesive; a circuit board disposed on the
upper surface of the crossbar; and a first conductor run and a
second conductor run disposed on the circuit board, wherein the
first lead of the light emitting diode unit is electrically
connected to the first conductor run and the second lead of the
light emitting diode unit is electrically connected to the second
conductor run.
16. The light fixture of claim 15, wherein the housing comprises a
thermally conductive material that is coated with a finish that
inhibits the flow of electric current.
17. A light fixture comprising: a housing comprising: a first side
and a second side, the first side comprising an inner surface
having a substantially straight portion, the second side comprising
an inner surface having a substantially straight portion; a
crossbar attached to the substantially straight portion of the
first side and to the substantially straight portion of the second
side, the cross bar comprising an upper surface and a lower
surface, wherein a mesa is defined on the upper surface, the mesa
being substantially parallel to the straight portions of the first
and second sides of the housing; a light emitting diode unit having
a lens, a base portion, a first lead, and a second lead, wherein
the base portion is attached to the mesa with a non-conductive
adhesive; a circuit board disposed on the upper surface of the
crossbar; and a first conductor run and a second conductor run
disposed on the circuit board, wherein the first lead of the light
emitting diode unit is electrically connected to the first
conductor run and the second lead of the light emitting diode unit
is electrically connected to the second conductor run, wherein the
light emitting diode unit is one of a plurality of light emitting
diode units, each of which has a base portion that is attached to
the mesa with a non-conductive adhesive, each of which has
respective first and second leads that are electrically connected
to conductor runs.
18. A light fixture comprising: a housing comprising: a first side
and a second side, the first side comprising an inner surface
having a substantially straight portion, the second side comprising
an inner surface having a substantially straight portion; a
crossbar attached to the substantially straight portion of the
first side and to the substantially straight portion of the second
side, the cross bar comprising an upper surface and a lower
surface, wherein a mesa is defined on the upper surface, the mesa
being substantially parallel to the straight portions of the first
and second sides of the housing; a light emitting diode unit having
a lens, a base portion, a first lead, and a second lead, wherein
the base portion is attached to the mesa with a non-conductive
adhesive; a first circuit board disposed on the upper surface of
the crossbar; a second circuit board disposed on the lower surface
of the crossbar, the second circuit board having disposed thereon
circuitry; and a first conductor run and a second conductor run
disposed on the circuit board, wherein the first lead of the light
emitting diode unit is electrically connected to the first
conductor run and the second lead of the light emitting diode unit
is electrically connected to the second conductor run, wherein the
first and second conductors are electrically connected to the
circuitry, the circuitry controlling the intensity of the light
emitted by the light emitting diode unit.
19. A light fixture comprising: a housing comprising: a first side
and a second side, the first side comprising an inner surface
having a substantially straight portion, the second side comprising
an inner surface having a substantially straight portion; a
crossbar attached to the substantially straight portion of the
first side and to the substantially straight portion of the second
side, the cross bar comprising an upper surface and a lower
surface, wherein a mesa is defined on the upper surface, the mesa
being substantially parallel to the straight portions of the first
and second sides of the housing; a light emitting diode unit having
a lens, a base portion, a first lead, and a second lead, wherein
the base portion is attached to the mesa with a non-conductive
adhesive; a circuit board disposed on the upper surface of the
crossbar; and a first conductor run and a second conductor run
disposed on the circuit board, wherein the first lead of the light
emitting diode unit is electrically connected to the first
conductor run and the second lead of the light emitting diode unit
is electrically connected to the second conductor run, wherein the
inner surface of the first side of the housing has an upper angled
portion and a lower angled portion, the substantially straight
portion being located between the upper angled portion and the
lower angled portion, wherein the inner surface of the second side
of the housing has an upper angled portion and a lower angled
portion, the substantially straight portion being located between
the upper angled portion and the lower angled portion, and wherein
the housing has a substantially H-shaped cross-section.
20. A light fixture comprising: a housing comprising: a first side,
the first side comprising an inner surface and an outer surface,
the inner surface of the first side having an upper angled portion,
a lower angled portion, and a substantially straight portion
disposed between the upper and lower angled portions, the outer
surface having a plurality of fins, a second side, the second side
comprising an inner surface and an outer surface, the inner surface
of the second side having an upper angled portion, a lower angled
portion, and a substantially straight portion disposed between the
upper and lower angled portions, the outer surface having a
plurality of fins, wherein the first and second sides are oriented
so that their respective inner surfaces face one another and are
spaced apart at a distance, a crossbar attached to the straight
portion of the inner surface of the first side and to the straight
portion of the inner surface of the second side such that the
crossbar spans the distance, the crossbar having an upper surface
with a mesa defined thereon, and a lower surface; a lens formed
with downward folds at its ends, the lens being disposed on the top
of the housing such that it acts as an end closure; a cover
disposed on the bottom of the housing, wherein the edges of the
cover fold upward such that they are oriented in substantially the
same direction as the first and second sides of the housing,
wherein the downward end folds of the lens of the housing are
constrained by the upward end folds of the cover; a first circuit
board disposed on the upper surface of the crossbar, the first
circuit board having a first conductor run and a second conductor
run, wherein a ground plane disposed on an upper surface of the
first circuit board, wherein mounting hardware connects the ground
plane to a chassis, and wherein the first and second conductor runs
are at least partly shielded from electromagnetic interference by
the ground plane; a light emitting diode unit that is attached to
the mesa with a thin layer of adhesive material, the light emitting
diode unit having a first lead and a second lead, the first lead
being electrically connected to the first conductor run, the second
lead being electrically connected to the second conductor run; and
a second circuit board disposed on the lower surface of the
crossbar, the second circuit board having control circuitry that
controls the intensity of the light emitting diode unit, wherein
the first and second conductor runs are electrically connected to
the control circuitry.
Description
FIELD OF THE INVENTION
This invention pertains to light fixtures and, more particularly,
to light fixtures that use light-emitting diodes and structures or
materials that dissipate heat generated by the light-emitting
diodes.
BACKGROUND OF THE INVENTION
Lighting systems for aircraft interiors are well known.
Conventional lighting systems include the use of fluorescent lights
to brighten the inside of an aircraft cabin. Fluorescent light is
used because it provides lighting sufficient to illuminate the
cabin so as to provide an environment that allows passengers and
cabin personnel to work and function comfortably. In addition to
light intensity, other advantages of fluorescent light include the
fact that it is energy efficient and highly reliable, factors that
are critical to commercial aviation. A problem associated with
fluorescent lighting is that it can, over an extended period of
time, become fatiguing to persons constantly exposed to the light.
Furthermore, while the light can be dimmed or brighten, the color
of the light cannot be changed.
An alternative to fluorescent lighting is light-emitting diode
(LED) based light. LEDs are also energy efficient but are easier on
the eyes of passengers. When employing LEDs in an aircraft cabin,
it is necessary to ensure that the heat generated by the LEDs is
adequately drawn away. Otherwise, there is a risk that the
semiconductor material of the LEDs will degrade quickly, thereby
requiring frequent replacement of the LEDs.
BRIEF SUMMARY OF THE INVENTION
The invention is generally directed to a light fixture suitable for
use in an aircraft. The light fixture is comprised of a housing
made of thermally conductive material, a circuit board supported by
the housing, and at least one light emitting diode unit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a light fixture configured according to an
embodiment of the invention;
FIG. 2 is a side view of a light fixture configured according to an
embodiment of the invention;
FIG. 3 is an end view of a light fixture configured according to an
embodiment of the invention; and
FIG. 4 is an example of a system in which an embodiment of the
light fixture described herein may be used.
DETAILED DESCRIPTION OF THE INVENTION
The invention is generally directed to a light fixture for use in
an LED lighting system for an aircraft. Referring to FIGS. 1 3, an
embodiment of the light fixture, generally labeled 10, includes a
housing 12 having a first side 14 and a second side 16. The first
and second sides 14 and 16 are displaced from one another. The
first side 14 has an inner surface that has an angled upper portion
46, a substantially straight portion 18, and an angled lower
portion 47. The second side 16 has an inner surface that has an
angled upper portion 48, a substantially straight portion 20, and
an angled lower portion 49. The length of the first side 14 is
longer that the height of the first side 14. Similarly, the length
of the second side 16 is longer that the height of the second side
16. A crossbar 22 is connected to the substantially straight
portion 18 of the inner surface of the first side 14 at
substantially at the mid-point of the height of the first side 14.
The crossbar 22 is also connected to the inner surface 20 of the
second side 16 at substantially the mid-point of the height of the
second side 16. The cross-bar 22 has an upper surface 24 and a
lower surface 26, and extends from the substantially straight
portion of the inner surface of the first side 14 to the
substantially straight portion 20 of the inner surface of the
second side 16. The upper portion 46 and substantially straight
portion 18 of the inner surface of the first side 14, the upper
surface 24 of the crossbar 22, and the upper portion 48 and
substantially straight portion 20 of the inner surface of the
second side 16 together define a first channel. Similarly, the
lower portion 47 and substantially straight portion 18 of the inner
surface of the first side 14, the lower surface 26 of the crossbar
22, and the lower portion 48 and substantially straight portion 20
of the inner surface of the second side 16 together define a second
channel. As can be seen in FIG. 3, the profile of the housing 12 is
substantially H-shaped.
Referring again to FIG. 3, a first printed circuit board (PCB) 28
is attached to the upper surface 24 of the crossbar 22. A thermal
pad (not shown) is attached to the lower surface 24 of the crossbar
22. A second PCB 30 is attached to the lower surface 26 of the
crossbar 22 such that the thermal pad is sandwiched between the
second PCB 30 and the crossbar 22. The first and second PCBs 28 and
30 and the thermal pad are secured to the crossbar 22 by screws
that are threaded through press fit inserts in the crossbar 22
and/or PCBs 28 and 30. The thermal pad carries heat from the PCB 28
into the housing 12 via the crossbar 22.
Referring again to FIG. 3, the upper surface 24 of the crossbar 22
defines a series of mesas 32 that run along the length of the
crossbar 22. As shown in FIGS. 1 2, disposed on top of the mesas 32
are twenty-four LED units, including six groups 42 of four LED
units each. Each group 42 of LED units is disposed on one of the
mesas 32. Within each group 42 of LED units, there are four
individual LED units 34--a white LED unit, a blue LED unit, a green
LED unit, and a red LED unit. It is to be understood that any
number, grouping, or color combination of LED units is possible,
however. For example, in one embodiment, there are twenty LED
units, including five groups of four LED units each. In another
embodiment, there are white and amber LED units, with a 2:1 ratio
of white LED units to amber LED units. In yet another embodiment,
there are green and red LED units, with a 2:1 ratio of green LED
units to red LED units. Furthermore, any suitable style of LED unit
may be used, including Lambertian or side emitter. The LED units 34
are mounted in a linear configuration, and may be evenly spaced or
grouped for optimum light mixing. In an embodiment of the
invention, multiple light units 12 are deployed in an aircraft
cabin and the groups of red, green, blue and white LED units of the
light fixtures allows for the generation of white light in excess
of 30 footcandles and accent lighting of any color (i.e.,
16,777,216 different colors).
Referring back to FIG. 3, the manner in which each of the LED units
is physically and electrically connected will now be described.
Each LED unit 34 has a lens 35 and a metallic base portion 36. The
dome portion 35 houses a high flux LED, whose heat is dissipated
through the metallic base portion 36. The base portion 36 is
attached to the mesa 32 of the crossbar 22 with an adhesive
material 38 that is electrically insulating, thereby preventing
stray current from leaking to the housing 12. In some embodiments,
however, the mesa 32 of the crossbar 22 is coated with an
electrically insulating paint, thereby allowing the use of an
electrically conductive substance as the adhesive material 38. The
adhesive material 38 may also have a low thermal conductivity, but
be applied in a thin enough layer (e.g. 1/3000th of an inch) to
allow sufficient heat to dissipate into the housing 12 from the LED
unit 34. One possible type of adhesive material that may be used is
an RTV silicone adhesive. The first PCB 28 has cutouts for
receiving the mesa 32 and the base portion 36 of the LED unit
34.
A first wire 40 electrically connects the positive lead of the LED
unit 34 to a first conductor run on the first PCB 28, and a second
wire 42 electrically connects the negative lead of the LED unit 34
to a second conductor run on the first PCB 28. The first and second
conductor runs are electrically connected to drive circuitry
located on the second PCB 30.
Certain features of the housing 12 will now be described with
reference to FIG. 3. The housing 12 is made of a thermally
conductive material, such as aluminum, which is coated with a
finish that inhibits the flow of electric current. When heat from
the LED units 34 reaches the housing 12 (via the base portion 36,
through the adhesive material 38, through the mesa 32, through the
crossbar 22), it conducts throughout the housing 12. The sides 14
and 16 of the housing 12 have fins 44 that radiate the heat.
Another feature of the housing 12 is that it enhances the overall
lighting qualities of the light fixture 10. For example, above the
crossbar 22, the substantially straight portions 18 and 20 of the
inner surfaces of the first and second sides 14 and 16 of the
housing 12 are prepared with a reflective material, such as
reflective tape, so that the substantially straight portions 18 and
20 mix the light emitted by the LED units 34 to provide consistency
of light patterns along the length of the housing 12. The angled
portions 46 and 48 of the inner surfaces of the first and second
sides 14 and 16 of the housing are also prepared with a reflective
material, such as reflective tape, and slope toward the LED unit
34, thereby approximating a parabolic reflector. This configuration
is intended to collimate light at the edge of the distribution area
of the LED units 34. Such light might otherwise be inefficiently
reflected around the inside of the housing 12. The reflective
material also helps to smooth light transitions between different
colored LED units 34.
The inner surfaces of the first and second sides housing 12 (FIG.
3) each have a lengthwise channel. A lens 50 is disposed within
these lengthwise channels. The lens 50 may be manufactured from
flame resistant polycarbonate or any other material that meets the
requirements of Federal Aviation Regulation 25.853. The lens 50 is
formed with downward folds at its ends such that it acts as an end
closure for the top part of the housing 12.
The housing 12 also includes a thin, formed aluminum cover 52 that
protects drive circuitry mounted on the PCB 30. Edges of the cover
52 fold upward to lay parallel to the bottom edges of the first and
second sides 14 and 16 of the housing 12, thereby allowing assembly
with simple hardware or swaged rivets. The downward end folds of
the lens 50 are constrained by the upward end folds of the cover 52
without the need for additional hardware. When installed in an
aircraft, a wire harness passes downward through grommets or cable
clamps at either one or both ends of the cover 52, which allows
light fixtures to be chained together sequentially.
In an embodiment of the invention, the packaging of the lighting
electronics of the light fixture 10 (FIGS. 1 3) is designed to
provide shielding for radiated electromagnetic interference (EMI)
by enclosing the circuitry in a ground conductive chassis. A copper
ground plane 39 is disposed on top of the first PCB 28. The
mounting hardware of the first and second PCBs 28 and 30 connects
the copper ground plane 39 to the chassis. Furthermore, conductors
on the first PCB 28, including the first and second conductor runs,
run primarily on the bottom of the first PCB 28, and are thus
shielded by this copper ground plane 39. Also, the thin sheet metal
of the bottom cover 52 is grounded to the housing 12 and can offer
shielding.
An example of a lighting system in which the invention may be used
is shown in FIG. 4. The lighting system, generally labeled 60,
includes multiple light fixtures 62. Each light fixture 12 is
electrically connected to the system 60 at a specific location
along a wiring harness. The system 60 also includes a master
controller 68 and multiple cabin controllers 70. The master
controller 68 executes one or more lighting programs and, according
to the program being executed, transmits data to each of the light
fixtures 12 in order to create lighting effects throughout the
cabin of an aircraft. The flight crew can select which program
should be executed by using the cabin controllers 70.
In can be seen from the foregoing that a new and useful light
fixture for an LED-based aircraft lighting system has been
described. Although example embodiments of the present invention
have been described in detail, those skilled in the art will
readily appreciate that many modifications are possible to these
embodiments without materially departing from the invention.
Accordingly, all such modifications are intended to be included
within the scope of this invention.
The use of the terms "a" and "an" and "the" and similar referents
in the context of describing the invention (especially in the
context of the following claims) are to be construed to cover both
the singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. Recitation of ranges of values
herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
* * * * *